The purpose of this study is to determine if 1) long-term cyclosporine A use is associated with a progressive toxic nephropathy; 2) circulating levels of elements of the coagulation system predisposing to formation of fiber predict progressive loss of renal allograft function; and 3) an incremental increase in GFR produced by oral administration of a protein load (i.e. "renal reserve") is a predictor of chronic renal allograft dysfunction.